- 1
- Sources: ECRI, 5200 Butler Pike, Plymouth Meeting,
PA 19462 USA (AHA DB); PhysioNet (http://physionet.org/) (MIT, NST,
CU DB; and ESC DB for non-commercial use); Alessandro Taddei, CNR
Institute of Clinical Physiology, G. Pasquinucci Heart Hospital, via
Aurelia Sud, 54100 Massa, Italy (ESC DB for commercial use).
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- 2
- Testing and Reporting
Performance Results of Ventricular Arrhythmia Detection
Algorithms. Publication AAMI ECAR (1987); succeeded by ANSI/AAMI
EC57:1998, available from AAMI, 1110 N Glebe Road, Suite 220,
Arlington, VA 22201 USA.
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- 3
- American National Standard for
Ambulatory Electrocardiographs. Publication ANSI/AAMI EC38:1998;
available from AAMI (address above).
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- 4
-
Source: Microstar Laboratories, http://www.mstarlabs.com/. External
analog anti-aliasing filters (to reduce “staircasing”) and attenuators (to
obtain patient-level signals) may also be required, depending on the system to
be evaluated. DAP boards can also be used with sample to create new
database records.
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- 5
- Times in annotation and signal files are usually expressed
as sample numbers (the number of samples in the signal file that precede
the sample in question).
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- 6
- Test annotations that include heart rate or ST
measurements require substantially more storage. getann and
putann can also use the original AHA DB format (containing fixed-length
annotations, 16 bytes each), but this format should not be used for
evaluations of devices that incorporate ST analysis functions, since the
space available for the aux data is too small to store ST measurements.
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- 7
-
The obvious alternative, using xform to rewrite the reference annotation
files at the time the signal files are resampled, should not be used in a
formal evaluation. Because of the possibility that resampling the reference
annotation files might result in moving reference annotations into or out of
the test period, or changing the lengths of episodes, doing so might produce
results that could not be directly compared with those obtained in a standard
evaluation.
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- 8
- See, for example, the European ST-T Database
Directory, pp. vi-vii, supplied with the ESC DB; or Taddei, A., et al., “The
European ST-T database: development, distribution, and use”, Computers
in Cardiology 17:177-180 (1990).
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- 9
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For certain types of HRV or RRV measurements (though not for heart rate
measurements), this is a potential problem. One solution is to add a small
positive offset to any measurement with an expected zero mean. It is within
the letter, though not the spirit, of the standard protocol, to add a
very large number in such a case, so as to make the error percentage
arbitrarily small. The mean value of the reference measurements must be
reported; this should serve as a disincentive to this sort of creative abuse
of the standard. An honest approach might be to add an offset on the order of
the expected standard deviation of the individual measurements.
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- 10
-
mxm is not restricted to comparison of heart rate measurements; if
other types of measurements are available, they may be compared in the same
manner as heart rates by mxm.
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- 11
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Annotation files for any given record are distinguished by annotator names,
which correspond to the “extension” of the file name. The
reference annotation files supplied with the databases have the annotator
name “atr” (originally “atruth” because “a”
was intended to indicate the file type, and “truth” because ...
well, because the annotations are supposed to be The Truth).
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- 12
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stm.out contains one line for each ST deviation measurement that was
compared; in this example, stm.out would be empty since the reference
annotation files of the MIT DB do not contain ST deviation measurements.
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- 13
-
wave (for FreeBSD, Linux, Mac OS X, Solaris, SunOS, and Windows)
are included in the WFDB Software Package.
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